While on a car trip with her family, Erin saw a sign that read, "Amarillo 100 miles, Lubbock 80 miles." She concluded that the distances from Amarillo to Lubbock is 100-80=20 miles. What she right?

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 0 a. at what time does the particle reverse direction? b. when is the displacement positive? (round one decimal place and answer in interval notation) c. when is the displacement negative? (round one decimal place and answer in interval notation) d. when is the particle’s acceleration positive? (round one decimal place and answer in interval notation) e. when is the particle’s acceleration negative? (round one decimal place and answer in interval notation)